<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        body{
          background-color: gray;
        }
        .big{
          width: 400px;
          height: 400px;
          background-color: pink;
        }
        .small{
          width: 100px;
          height: 100px;
          background-color: red;
          border-radius: 50%;
          overflow-wrap: break-word;
        }
      </style>
</head>
<body>
    <div class="big">
        <div class="small">
          ddddddddddddddddddddddddddddddddddddddddddd
        </div>
      </div>
</body>
</html>